The invention relates to a withdrawable multipole circuit breaker which is able to be moved in translation between two end of draw-in and extraction travel positions, inside a frame shaped as a parallelipipedic housing, comprising an opening in the front panel enabling the circuit breaker to be extracted and a rear wall opposite the circuit breaker passage opening, said wall being equipped with an insulating support through which fixed connection terminals pass, each comprising a first part external to the housing for electrical connection, notably to an external busbar, and a second part internal to the housing on which is mounted a draw-in grip securedly fixed to the frame, said grip cooperating in the drawn-in position with a corresponding contact terminal of a pole of the circuit breaker.
According to a known withdrawable circuit breaker, each draw-in grip is fixed directly by assembly means to the rear wall of a low voltage cubicle frame. A three-phase circuit breaker requires six draw-in grips to be fitted on the frame. The manufacturing cost of such frames is relatively high, and inspecting the grips when maintenance operations are carried out is complicated, as the rear wall of the frame has to be partially dismantled.
It has also been proposed to fit the draw-in grips on the circuit breaker contact terminals by means of a double clip-on system ensuring bilateral gripping on both the opposite sides of the contact terminal. A device of this kind is described in U.S. Pat. No. 3,427,419. Fitting and removing this type of grips nevertheless still remain difficult.
The object of the invention is to make draw-in grip fitting and removal operations easy, and to use a standard frame designed to be individualized in the final phase of the assembly operation by a judicious choice of the draw-in grips and connection terminals in terms of the circuit breaker rating, the type of terminal connection and the electrodynamic withstand of the grips.